AN UPDATED DISTRIBUTION MAP for the LOWER COLORADO RIVER VALLEY POPULATION of GREATER SANDHILL CRANES Blake A
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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Proceedings of the North American Crane North American Crane Working Group Workshop 2018 AN UPDATED DISTRIBUTION MAP FOR THE LOWER COLORADO RIVER VALLEY POPULATION OF GREATER SANDHILL CRANES Blake A. Grisham Daniel P. Collins Kammie L. Kruse Courtenay M. Conring Jeffrey M. Knetter See next page for additional authors Follow this and additional works at: http://digitalcommons.unl.edu/nacwgproc Part of the Behavior and Ethology Commons, Biodiversity Commons, Ornithology Commons, Population Biology Commons, and the Terrestrial and Aquatic Ecology Commons This Article is brought to you for free and open access by the North American Crane Working Group at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Proceedings of the North American Crane Workshop by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Blake A. Grisham, Daniel P. Collins, Kammie L. Kruse, Courtenay M. Conring, Jeffrey M. Knetter, and Warren C. Conway AN UPDATED DISTRIBUTION MAP FOR THE LOWER COLORADO RIVER VALLEY POPULATION OF GREATER SANDHILL CRANES BLAKE A. GRISHAM,1 Department of Natural Resources Management, Texas Tech University, Plant and Soil Sciences Building, P.O. Box 42125, Lubbock, TX 79409, USA DANIEL P. COLLINS, U.S. Fish and Wildlife Service, Migratory Bird Office-Region 2, P.O. Box 1306, Albuquerque, New Mexico 87103, USA KAMMIE L. KRUSE, U.S. Fish and Wildlife Service, Migratory Bird Office-Region 2, P.O. Box 1306, Albuquerque, New Mexico 87103, USA COURTENAY M. CONRING,2 Department of Natural Resources Management, Texas Tech University, Plant and Soil Sciences Building, P.O. Box 42125, Lubbock, TX 79409, USA JEFFREY M. KNETTER, Idaho Department of Fish and Game, 600 S. Walnut St., P.O. Box 25, Boise, ID 83707, USA WARREN C. CONWAY, Department of Natural Resources Management, Texas Tech University, Goddard Building, P.O. Box 42125, Lubbock, TX 79409, USA Abstract: The U.S. Fish and Wildlife Service (USFWS) recognizes 6 migratory populations of sandhill cranes (Grus canadensis) in the United States, 4 of which occur in or west of the Rocky Mountains. Traditionally the Lower Colorado River Valley Population (LCRVP; greater sandhill crane [G. c. tabida]) was thought to be distributed across the Imperial (California) and Lower Colorado River (Arizona) Valleys, southward into Mexico via the Colorado River delta in winter and northeastern Nevada (Elko and White Pine Counties) during summer. Conservation and management concern exists over known distribution based on winter and summer surveys because discrepancies exist between the number of individuals counted on winter and summer termini. In 2014 the USFWS initiated a mark-recapture program on the LCRVP to aid in the development of long-term management of this least abundant greater sandhill crane population. The objective of this paper is to update the known distribution of the LCRVP from greater sandhill cranes by using platform transmitter terminals (PTTs). We captured 44 individual greater sandhill cranes and equipped 22 with PTTs on the wintering and summering grounds in the Imperial and Lower Colorado River Valleys and west-central Idaho, 2014-2015. Our updated distribution map from 18 of 22 PTT-tagged individuals identified several new summer locations extending north and west into west-central Idaho and numerous new migratory locations extending east into Utah. We also confirmed winter locations on the Gila River southwest of Phoenix, Arizona. The extent of the distribution of the LCRVP extends farther north and east than previously expected and, most importantly, overlaps with areas commonly affiliated with the Central Valley and Rocky Mountain Populations in the Intermountain West. PROCEEDINGS OF THE NORTH AMERICAN CRANE WORKSHOP 14:1-9 Key words: distribution map, greater sandhill crane, Grus canadensis tabida, Lower Colorado River Valley Population, platform transmitter terminals. The U.S. Fish and Wildlife Service (USFWS) the only population of the 4 not wintering in southern recognizes 6 migratory populations of sandhill cranes California. The other 3 populations (PC, CVP, LCRVP) (Grus canadensis) in the United States (Fig. 1). Four have adjacent wintering grounds in river valleys of the 6 populations, the Pacific Coast (PC), Central associated with desert or mountain ecosystems in Valley (CVP), Lower Colorado River Valley (LCRVP), central and south California (Fig. 1). Specifically, the and Rocky Mountain (RMP), are distributed in or west LCRVP winter termini consists of the Imperial Valley in of the Rocky Mountains. The RMP primarily winters southern California and Lower Colorado River Valley along the Middle Rio Grande River Valley in central in Arizona, with some evidence of additional winter New Mexico, Willcox Playa in southeast Arizona, and locations on the Gila Bend along the lower Gila River the Interior Highlands in Chihuahua, Mexico, and is southwest of Phoenix, Arizona (Pacific Flyway Council and USFWS 1995, Pacific Flyway Council 2017). The LCRVP is the least abundant of the migratory greater sandhill crane (G. c. tabida) populations in the 1 E-mail: [email protected] 2 Present address: Alabama Department of Conservation and Natural Intermountain West with an estimated 2,716 individuals Resources, 234 County Road 141, Hollywood, AL 35752, USA (Dubovsky 2017) based on winter counts. The 1 2 UPDATED DISTRIBUTION OF LCRVP SANDHILL CRANES • Grisham et al. Proc. North Am. Crane Workshop 14:2018 Figure 1. Approximate nesting, winter, and primary migration staging areas of the 6 migratory sandhill crane populations (from Collins et al. 2016). Areas depicted in this figure are generalizations and show relative position of migratory ranges; the ranges of each migratory population are still being determined in North America. conventional wisdom was that the LCRVP summered (Pacific Flyway Council and USFWS 1995). Survey exclusively in northeastern Nevada and migrated south data in northeastern Nevada, however, only account for in a very linear fashion to winter along the Lower ~30% of those counted on the winter termini (Conring Colorado River Valley, Imperial Valley of California, 2016, Pacific Flyway Council 2017). These data and in Mexico on the Colorado River delta region suggest that the LCRVP does not exclusively summer Proc. North Am. Crane Workshop 14:2018 UPDATED DISTRIBUTION OF LCRVP SANDHILL CRANES • Grisham et al. 3 in northeastern Nevada, and other cranes wintering Refuge (NWR) (33.318°N, 114.698°W), which along the LCRV and Imperial Valley may be from encompasses 6,988 ha of land in La Paz County, different migratory populations. Nevertheless, efforts to Arizona, and Imperial County, California. Cibola NWR expand and conduct surveys (aerial and ground surveys, is located on the main branch of the lower Colorado mark-recapture) on the breeding grounds to locate River. We also captured 12 and 2 cranes on 13,259 new areas within the large geographic distribution ha near Brawley (32.588°N, 115.318°W) and Sonny of the Intermountain West is time consuming and Bono Salton Sea NWR (33.158°N, 115.738°W), difficult. As such, the delineation of greater sandhill respectively, in the Imperial Valley of California. The crane populations in the western United States entire Imperial Valley, including Sonny Bono Salton potentially excludes numerous migratory, summer, and Sea NWR, is surrounded by Sonoran Desert uplands. winter locations of 3 of the 6 migratory populations. All cranes captured in Arizona and California were in Meticulous delineation of the migratory populations adult plumage but a more specific age class (subadult in the West is important for long-term conservation of or adult, i.e., < or ≥ 3 years old, respectively) was not greater sandhill cranes due to various harvest guidelines determined. as well as varying state-level conservation status for We opportunistically captured 5 cranes as flightless greater sandhill cranes in Arizona, California, Colorado, colts on their natal territories in Idaho (44.528°N, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, 116.058°W) in collaboration with the Idaho Department Washington, and Wyoming. For example, greater of Fish and Game. We scouted for breeding pairs of sandhill cranes are a state-level threatened species in cranes to locate colts starting near Boise, Idaho, and California and Washington, but are harvested in other then moved north to the Long Valley, and then east to the western states (e.g., Arizona and New Mexico). Bear Valley and southeast to the Camas Prairie Wildlife In 2014, USFWS Southwest Region initiated a Area near the town of Fairfield (43°20′N, 114°47′W). mark-recapture program on the LCRVP winter grounds We used rocket nets and noose snares in upland to provide additional data for long-term management. areas away from roost sites to capture wintering cranes at Specific goals of the mark-recapture program were to Cibola NWR and Sonny Bono Salton Sea NWR during quantify habitat selection, assess migratory routes and January and February 2014 and January 2015 (Wheeler summer distribution, and assess overwinter spatial and Lewis 1972, Urbanek et al. 1991, Hereford et al. ecology of the LCRVP by using platform transmitter 2001). We captured colts on the summering grounds terminals (PTTs) (Collins et al. 2016, Conring 2016, in Idaho by hand with dip nets (68 × 78 cm; 121 cm Kruse et al. 2017). Also, intermixing on the summer deep with 121-cm handle) in July 2014 and 2015. We and migratory areas has been previously identified from used plumage characteristics to distinguish adult cranes preliminary samples used herein (Collins et al. 2016). from hatch-year cranes in instances where we were Our objectives were to create an updated distribution targeting adults on the wintering grounds (Lewis 1979, map of the LCRVP that identifies 1) migratory pathways, Krapu et al. 2011). A 22-g solar-powered PTT was 2) summer distribution, and 3) winter distribution using mounted on a 2-piece leg band with one-half engraved location data from PTT-tagged greater sandhill cranes with a unique alpha-numeric code.